In medicine, needle punctures of anatomical structures, whether for diagnosis (biopsies) or for therapy (injections, drainage, etc.), represent a common and frequent intervention. Puncture needles are used which are inserted through the patient's skin and advanced until they reach a defined target (often a tumor or a metastasis). It is of particular importance in this respect that the needle is aligned precisely with the target before insertion. Various imaging techniques can be used to visually monitor the alignment procedure and the actual insertion of the needle. The most common imaging methods used for this purpose are ultrasound, fluoroscopy or computed tomography.
In fluoroscopy and computed tomography, X-rays are used to obtain the images. Handling surgical instruments or a puncture needle near to the X-ray field or even within the X-ray field exposes the physician to considerable radiation levels. Although lead aprons and other protective measures reduce the radiation dose, the radiation exposure of the physician's hands themselves is still significant.
Devices taking over the manipulation of the instruments in the X-ray field would be of help here. The physician would operate the devices manually or by remote control outside the X-ray field, depending on whether the device concerned is a passive or active (motorized) device.
In the case of tissue removal, the needles used are either biopsy punch needles (diameter 1 to 2.5 mm) for obtaining tissue samples for histological examination, or fine needles (diameter ca. 0.8 to 1.4 mm with a length of up to 20 mm) for aspiration biopsy for cytological tissue samples. Ever finer needles are used for injections.
The thinner and longer the needles however, the greater the danger of the needle buckling. When inserting the needle by hand, the physician has to take care to guide the needle steadily and without it buckling. For this purpose, fine needles are in most cases held tightly with one hand at the point of insertion and the other hand is used to apply the driving force at the end of the needle.
If the needle is to be inserted by remote devices, that is to say driven by a motor, then the danger of the needle buckling takes on particular importance.
From EP-A-0 682 910, EO-A-0 595 291 and U.S. Pat. No. 5,882,294, it is known in devices of the type, to divide the guide into two sections and to provide between both sections drive devices which cooperate with frictional engagement to drive the needle.
From U.S. Pat. No. 4,383,532 and DE 94 16 957 U it is also known, by use of an articulated arm, to provide for pivoting about a defined point of rotation in such a way that the articulated arm effects a pivoting movement of the needle about a first axis and a second axis, and in each case in a plane containing the point of rotation.